It is well known there is a difficult problem involved in providing interior maintenance to spherical tanks, because of the inaccessibility of points inside because of the volume and great size which they may have, when it is necessary to carry out maintenance inspection thereof. The latter are of vital importance, since liquids or gases are stored therein under pressure, or solvents or liquids the safe keeping of which is imperative.
Structures have been designed to carry out inspection while assembly is under way, or for the construction and inside assembly of pieces within the said spherical tanks, such as the case of U.S. Pat. No. 4,068,419, which shows a central tower supported on a fixed base and shows structural scaffolding supported by cables which run from the said central tower to the remote points which it is desired to inspect or provide maintenance to; the said structure is fixed. Which leads to the necessity of using a large number of scaffolds, communicating at their ends by means of catwalks. All of this requires a large quantity of structural elements, as well as numerous personnel for their installation, and a large amount of manhours for their assembly; and these factors make it relatively impractical and of high cost because of the materials and working time employed.
The advantages of the present invention over the known mechanisms resides primarily in the innovation of a gyratory element with vertical elevation and descent, by means of which any inside point can be reached as needed without requiring a large number of structural elements inside the spherical containers. Furthermore in the present invention the articulations are controlled by winches and cables which are easily handled and very efficacious for reaching any point on the inside of the structure as may be desired, by rotating the central towers and causing the basket-supporting arms to rise or descend. The latter in turn enjoy independent movement since each one is mounted on a respective one of the central towers. The working baskets are secured to the supporting arms, and thus there is no need to perform extra work upon the walls of the container for securing or supporting work units or baskets. The working units are constructed within the baskets with sufficient space for operators therein as well.